The present disclosure relates to a liquid administration instrument.
An injection device used when drug solution is administrated is known (for example, refer to Japanese Patent No. 4176631). The injection device disclosed in Japanese Patent No. 4176631 includes a main body portion which has a cylindrical shape and in which drug solution is filled aseptically, a needle tube fixed to a distal portion of the main body portion, a gasket (stopper) capable of slidably moving in the inside of the main body portion, a plunger configured to engage with a proximal side of the gasket and press the gasket in a direction toward the distal end to discharge drug solution from the needle tube, and a cover member (shield) capable of covering the needle tube. When drug solution is administrated using an injection device having such a configuration, the needle tube punctures a living body in a state in which the cover member is moved backwards until the needle tube is exposed, and then the plunger is operated and pressed as it is. Consequently, the drug solution is discharged from a aperture by the gasket and can be administrated into the living body through the needle tube. After the administration of the drug solution is performed, if the needle tube is pulled out from the living body and the cover member is moved forwards, then the needle tube is covered with the cover member to allow the injection device to be discarded safely. It is to be noted that the injection device disclosed in Japanese Patent No. 4176631 is configured such that, if the needle tube is covered by forward movement of the cover member, then the cover member is prevented from being moved backwards again. Consequently, the state in which the needle tube is covered with the cover member after the administration can be maintained with certainty.